Spirit-level.



N0 MODEL.

PATBNTED OCT. 11, 1904.

J. BISHOP.

SPIRIT LEVEL.

APPLICATION FILED 06126. 1903.

INVENTOH Lia/272 1923/20 29 A 770/?NE YS UNITED STATES Patented. October 11, 1904.

JOHN BISHOP, on BARTOW, FLORIDA.

SPIRIT-LEVEL.

SPECIFICATION forming part of Letters Patent No. 771,803, dated October 11, 1904.

Application filed October 6, 1903. Serial No. 175,956. (No model.)

To wi l whom it may concern:

Be it known that 1, JOHN BISHOP, a citizen of the United States, and a resident of Bartow, in the county of Polk and State of Florida, have invented a new and Improved Spirit- Level, of which the following is a full, clear, and exact description.

My invention relates to improvements in levels; and the object that I have in View is the provision of an improved spirit-level in which the contradistinction between the tube and the liquid therein shall be so clear that the airbubble present in levels of this type may be readily and easily seen in a very poor or dim light and at a reasonable distance.

Heretofore difficulty has been experienced with levels of the type to which my invention pertains owing to the fact that in a faint light it is very often impossible to discern the air bubble in the glass, and this fact frequently causes considerable inconvenience, especially when it is necessary to use the level in dimly-lighted places, such as tunnels, mines, cellars, and the like. Many attempts have been made to obviate this inconvenience by various expedients, such as pasting a strip of colored material around the level; but I have found by experiment that such a method is not successful and satisfactory, because the air-bubble can only be seen while looking directly down upon the level and then only when the instrumentis held in close proximity to the eye of an observer.

With a device constructed in accordance with my invention it is possible to observe the bulb or the bubble from any angle or side and in very faintly or dimly lighted places. 7

My invention consists of a spirit-level comprising a tube and an opaque liquid within the tube, said tube havingabackground contrasting in color to the liquid and visible through the air-bubble.

The invention further consists in the employment of a member disposed lengthwise of joined description and the actual scope thereof will be defined by the annexed claims.

Reference is to be had to the accompanying drawings, forming a part of this specification, in which similar characters of reference inclicate corresponding parts in all the figures.

Figure 1 is a plan View of a glass or spiritlevel embodying my invention. Fig. 2 is a longitudinal sectional elevation thereof, and Fig. 3 is a cross-section on an enlarged scale.

In carrying my invention into practice I employ a tube, such as 5, which is formed of any suitable transparent material, such as glass,the end portions of said tube beingclosed, as at 6, in any suitable way. The tube is filled with a liquid which is colored in any desired manner, such as by indigo-blue, which coloring 1 have found to be very suitable. The colored liquid which I employ is substantially or practically opaque, so that the light will not pass or penetrate through the tube and the liquid contents thereof.

To render the air-bubble plainly visible at all times, except, of course, in the dark, 1 provide the tube with a background which is of a different color from the liquid and which is plainly visible through the air-bubble when viewed either from the side or the top of the level. The colored liquid and the member which furnishes the background are of con-.

trasting colors in order to render the air-bubble visible at aglance, and in one embodiment of the invention the background is afforded by a member which ranges lengthwise ofthe tube and is practically immersed within the opaque-colored liquid thereof.

As shown by Figs. 2 and 3 of the drawings, the background member is in the form of a rod, stem, or spindle,(indicated at 7,) the same extending lengthwise of the glass and arranged centrally therein. This member may be made of glass, metal, or any other appropriate material, and it is adapted to be confined within the tube in any suitable way; but, as shown by Fig. 2, the end portions of this member are provided with heads 8, which fit from endwise or lateral displacement within the tube by the provision of the heads, and this member is made of a dilferent color from the opaque liquid by making it of light material or by giving the member a suitable coating. Under some circumstances I make the member of White or light-colored glass, whereas the opaque liquid is of a dark-blue color, thus affording a good contrast; but in other cases I may change the color of the opaque liquid, and I may also employ a member which is silver-coated.

The broad feature of my invention resides in the employment of an opaque liquid and a background within the tube of the level. The background may be formed Within the tube by the employment of the member 7 or by any equivalent means, and as the liquid is of an opaque nature the member will be concealed except where the bubble exposes it. This feature of the level differentiates it from other prior levels of which I have knowledge, in which the liquid is of a transparent nature and the background is plainly visible through said liquid.

In the drawings I have shown the level on an enlarged scale in order to clearly represent the construction; but it is to be understood that I do not confine myself to any particular A size nor to the proportions of the parts shown by the drawings.

Having thus described my invention, I claim as new and desire to secure by Letters Patent 1. In a spirit-level, a tube containing a liquid, and a background in the tube contrasting in color to the liquid of the tube, said background being held approximately at the center of the tube and visible through the airbubble.

2. A level comprising a tube, a background member therein, and an opaque liquid within said tube, said background contrasting in color to the liquid, and concealed except at the place where it is exposed through the air-bubble.

3. A level comprising a tube, a member within said tube and presenting a background, and an opaque liquid contrasting in color to the member and concealing the latter except where it is exposed through an air-bubble.

4. A level comprising a tube, a member ranging lengthwise of said tube and presenting a background, and an opaque liquid contrasting in color to the member and concealing the latter except where the background is visible through the air-bubble.

5. A level comprising a tube, an opaque liquid therein, and a member immersed in and concealed by the opaque liquid except Where exposed through an air-bubble, said member presenting a background which contrasts in color to the opaque liquid.

6. A level comprising a tube, an opaqueliquid therein, and a member ranging lengthwise of the tube and held against movement or displacement therein, said member contrasting in color to the opaque liquid, and presenting a background which is concealed except where it is visible through an air-bubble.

7. A level comprising a tube, a liquid therein, and a member ranging lengthwise of the tube and provided with heads which fit Within the tube, said member contrasting in color to the liquid.

In testimony whereofI have signed my name to this specification in the presence of two subscribing Witnesses.

JOHN BISHOP.

Witnesses:

FRITZ WUTHRIOH, FLETCHER MoRRIsoN. 

